Lower hybrid heating in ELMO Bumpy Torus

Abstract

Absorption of lower hybrid wave energy by the electron and ion plasma components in the ELMO Bumpy Torus (EBT) is examined. The wave and plasma parameters used are those appropriate for the EBT-Scale (EBT-S) and EBT Proof-of-Principle (EBT-P) devices. The computations are carried out using a ray-tracing code that was developed at the Oak Ridge National Laboratory for the study of electron cyclotron heating in EBT. Along the ray trajectory, electrons absorb the lower hybrid wave energy by electron Landau damping. The lower hybrid rays are followed until they reach the location where the condition for mode conversion to an ion Bernstein mode is satisfied. The remaining lower hybrid energy is then assumed to be deposited in the ion component. We find that, with careful matching of wave and plasma parameters, lower hybrid power could be used to heat the ions near the centre of the plasma in both EBT-S and EBT-P. The parameter ranges for lower hybrid heating of the ions are more limited for EBT-P than for EBT-S.